|Title||Linear weakening of the AMOC in response to receding glacial ice sheets in CCSM3|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||Zhu J, Liu Z.Y, Zhang X., Eisenman I, Liu W|
|Journal||Geophysical Research Letters|
|Type of Article||Article|
|Keywords||age; Atlantic Meridional Overturning Circulation; atlantic thermohaline circulation; carbon-dioxide; cycle; deglaciation; global climate-change; ice; ice sheet retreat; last; model; sea ice transport; sheet orography; simulations; stability; surface|
The transient response of the Atlantic Meridional Overturning Circulation (AMOC) to a deglacial ice sheet retreat is studied using the Community Climate System Model version 3 (CCSM3), with a focus on orographic effects rather than meltwater discharge. It is found that the AMOC weakens significantly (41%) in response to the deglacial ice sheet retreat. The AMOC weakening follows the decrease of the Northern Hemisphere ice sheet volume linearly, with no evidence of abrupt thresholds. A wind-driven mechanism is proposed to explain the weakening of the AMOC: lowering the Northern Hemisphere ice sheets induces a northward shift of the westerlies, which causes a rapid eastward sea ice transport and expanded sea ice cover over the subpolar North Atlantic; this expanded sea ice insulates the ocean from heat loss and leads to suppressed deep convection and a weakened AMOC. A sea ice-ocean positive feedback could be further established between the AMOC decrease and sea ice expansion.